Butadiene 1, 3-acrylonitrile rubbery copolymers with improved lowtemperature flexibility



Patented Aug. 16, 1949 UNITED STATES 2,479,018 noranmur: 1,3-ACRYLONITRILE RUBBERY COPOLYMERS WITH IMPROVED LOW- TEMPERATURE FLEXIBILITY Leonard Nicholl, Nyack, and George Kesslin, New

York, N. Y., assignors to .Inc., West Haverstraw,

New York Kay-Fries Chemicals, N. Y., a corporation of No Drawing, Application June 5, 1946,

Serial No.

3 Claims. (01. zoo-31.8)

This invention relates to butadiene 1,3-acrylonitrile rubbery copolymers, and, more particularly, to such rubbery copolymers incorporating dip-isobutyl sebacate as a plasticizer. This application is a continuation-in-part of our application Ser. No. 512,638, flied December 2, 1943, for Di-p-isobutyl sebacate, now Patent No. 2,403,804, issued July 9, 1946.

Hitherto, the cellulose esters, vinyl resins, rubber hydrochloride derivatives, and other thermoplastic and thermosetting resins have been plasticized by a wide variety of compounds, including various esters of polybasic carboxylic acids, such as the phthalates, sebacates, adipates, etc. However, compounds which have been found to be useful as plasticizers for such thermoplastic and thermosetting resins, are found to be wholly unusable with elastomers of the butadiene 1,3-acrylonitrile rubbery copolymer type.

Conversely, plasticizers which are compatible with butadiene 1,3-acrylonitrile rubbery copolymers, are incompatible with oellulosic esters, etc, in spite of the very'close family relationships existing between the groups of plasticizers. So much so, that in this field, analogical reasoning leads only to confusion, and-it is not possible to predict what the effect of any given compound, as a plasticizer, will be on a plastic composition, until it has been tried out under commercial operating conditions.

In the present day accelerated development of synthetic rubber plastic compounds, or, more properly speaking, rubbery copolymers, there has been a crying need for plasticizers which will impart to the rubbery copolymers a desired low temperature flexibility. In the use of synthetic rubbers for equipment in polar regions under subarctic conditions, as well as. for industrial uses in refrigeration and low temperature work generally, it has been found that synthetic rubbers are not plasticized or flexibilized properly, to standunder low temperature working conditions. Thisis particularly true with the general run of plasticizers used for rubber and rubber substitutes. In the development of the newer synthetic rubbers, including those of the butadiene 1,3-acrylonitrile types, frangibility at low temperatures is very marked. This condition has been overcome by incorporating therewith a suitable plasticizer, such a di-p-isobutyl sebacate recently prepared and discovered by us. This 'compound may be incorporated in varying amounts in rubbery copolymers of the butadiene 1,3-acrylonitrile type, although in amounts varying from 10 to 25% of the rubbery copolymer it has been found to give excellent results, particularly the much desired low temperature flexibility now so highly sought after. y

The results of the incorporation of diisobutyl sebacate as a plasticizer in butadiene 1,3-acrylonitrile rubbery copolymers are shown in the following test report wherein comparison is made of the plasticlzing effects of equivalent mixtures of the above copolymers with plasticizers comprising triethylene glycol diheptoate, tributoxy ethyl phosphate, and dibutyl phthalate. Tributoxy ethyl phosphate and dibutyl phthalate are well known plasticizers for butadiene 1,3-acrylonitrile copolymers, and are used as standards of comparison.

Copy of testsrun on sample di isobutyl sebacate in comparison 5 with other plasticizers DiIso Butyl Tributoxy Ethyl 4 sebacate Plasticizer "so" Phosphate DiButyl Phthalate Min. Cure 310 F 20 a0 45 20 3o I 45 20 50 45 20 a0 45 Mod. 500% 900 915 1,115 1,050 1,225 1,115 1,250 1,400 1,550 900 1,150 1.250 Ult. Tensile 1,800 1,950 1,110 2, 310 2. 215 2. 410 2,200 2, 950 2, 550 2.125 2, 350 2. 100 Uit. Elongation 455 450 915 505 450 495 495 455 425 505 515 415 Tens. Sheet Hardness 40 42 4s 41 41 45 45 45 45 45 41 Flexible to F -s5' --a5 -86 -s5 Brittle at F -104 -04 -104 -04 100% Flex. (286 r. P.

Pin Method 5. 500 2. 900 5, 905 5, 255 s Gr 1. 11 1. 1s 1. 20 1. 20

14" Disc Cured 310 F... 45 00 45 00 45 45 50 Shore Hardness 42 I 43 45 46 47 47 48 48 Per Cent Lupke Rebound 15 15 15 15 15 12 15 13 Per Cent Comp. Bet ASTM- 11 1a 15 12 21 1 15 12 11 Copy of tests run on sample di isobutul sebacate in comparison with other plasticizers-Continued Di Lao Butyl Plaeticizer Di Butyl Sebacate "so" aggi Phthelete Per Cent Volume Change, ASTM-SAE Oil, Aniline Pt.

159 F., 70 hrs. at 212 F .l 4 863 +3 2.16 Per Cent Volume Change, Ethylene Glycol, 70 hrs. at 212 F +8 +2. 06 1. 59 Per Cent Volume Change, Aromatic Gas, 70 hrs. at

Room Temip +1. 59 +4 +9 +6 Flexible to 'Al'ter ASTM-SAE 70 hrs. at 212 F 32 22 --m -22 Flexible to F. After Paraflln Lub. Oil, Aniline Pt. 240 F.,

70 hrs. at 212 F -32 22 -22 -22 Flexible to F. After Ethylene Glycol, 70 hrs. at 212 F 08 5O --40 Flexible to T. Alter Distilled Water, 70 hrs. at 212 F --68 68 l58 58 Flexible to F. After 100 Octane Gas, 70 hrs. at Room Temp -58 i58 58 Flexible to F. After 20% Aromatic Gas, hrs. at Room Temp 94 --94 94 94 Brittle at F. After ASTM-SAE Oil, Aniline Pt. 150 F.,

70 hrs. at 212 F 76 76 76 76' Brittle at After Perafiln Lub. Oil, Aniline Pt 240 F 70 hrs. at 212 F -76 86 86 86 Brittle at T. After Ethylene Glycol, 70 hrs. at 212 Below 104' Below -104 Below 10-i l04 Brittle at F. Alter Distilled Water, 70 hrs. at 212 F -104 -94 Brittle at F. After Octane Gas, 70 hrs. at Room Temp. Below -104 Below 104 Below l0l Below l04 Brittle at F. After 20% Aromatic Gas, 70 hrs. at Room Temp Below -104 l04 Below 104 Below -104 180 Bend, Air Oven Aged, 48 hrs. at 300 F. OK OK OK OK 180 Bend, Air Oven Aged, 70 hrs. at 212 F OK 0K OK OK Heat Loss, Air Oven Aged, 48 hrs. at 300 F l7 -10 10 -18 Heat Loss, Air Oven Aged, 70 hrs. at 212 F -12 -3 3 -1.21

Air Oven Air Oven Air Oven Air Oven Aged 70 Aged 70 Aged 70 Aged 70 hrs. at hrs. at hrs. at hrs. at 212 F 212 F. 212 F. 212 F.

Ultimate Tensile 2. 890 1, 700 2, 026 2, 000 Ultimate Elongation- 205 225 280 2% Shore Hardness 70 67 50 07 A typical distillation run is as follows:

[Total weight of batch-806 lbs] vapor temperature approximately 97 C. 100% Acidity es Erect. Liq. '1 Vap. '1. Press 323%,? gg seAbaiaio Remarks Degrees Degrees Mm. Pounds Per cent Per amt 1 78-145 0560 -2 132 Practically pure isobutyl alcohol. 2 1 154 2 41 98.8 .081 Good product. 3 154 154 2 675 99. 2 081 0.

e 51 Residue.

The reaction described above can be graphically a esterification of the acid by the alcohol is indiillustrated by the following equation:

coon coo-onlr srr-cm & E2804 2) H2)a+2CHaGH-CH, OH Hm +2H=o cos: n; ooomcn-cm Sebaclo (Prim isobutyl acid) 8135101) (Di 112153;; aiobutyl The novel compound of the present invention may be prepared in the following manner: 670 lbs. of p-isobutyl alcohol are charged into a galion still. The liquid is raised to a temperature of approximately 80 C. and while stirring, 435 lbs. of 97.5% sebacic acid are added as rapidly as convenient, and usually in a one to two hour time period. To the mixture in the still there is added 3.8 lbs. of concentrated sulphuric acid as a catalyst, and the still is closed. The temperature of the reaction mixture is increased until the liquid temperature has risen to approximately 99 C. In a practical operation, at this temperature, a constant boiling mixture or p-isobutyl alcohol and water forms and begins to distill over.

cated when a test sample on titration requires approximately .8 cc. of N/10 NaOH per 1 cc. of sample. The crude ester product is then treated with 7.8 lbs. of anhydrous sodium carbonate (100% excess for the indicated acidity). The crude product is then distilled without a dephlegmator and under a low vacuum of 14.0 mm. to remove residual primary isobutyl alcohol. Thereafter the di-p-isobutyl sebacate'is distilled over, preferably under a high vacuum of 2 mm. to 4 mm. with corresponding variations in liquid temperature. Generally, the more the pressure used approaches atmospheric pressure, the higher the distillation temperature will have to be.

It will now be appreciated that there has been disclosed a novel compound di-p-isobutyl sebacate, compounded with an particularly suited as a plasticizer for elastomers comprising rubbery copolymers of the butadiene 1,3 acrylonitrile type, and particularly adapted to impart "low temperature flexibility to them and other elastomers.

What is claimed is:

1. As a composition of matter, a butadiene 1,3- acrylonitrile rubbery copolymer, including 20-25% of di-p-isobutyl sebacate based on the weight of the copolymer.

2. As a composition of matter, a butadiene 1,3- acrylonitrile rubbery copolymer characterized by "low temperature" flexibility and including Of di-p-isobutyl Sebacate (In th. weight of the copolymer.

3. As a composition of matter, a butadiene 13- Number m Date acrylonitriie rubbery copoiymer, including 25% 2,403,804 Kenalin July 9, 1946 of di-p-isobutyl sebacate based on the weight of 5 OTHER REFERENCES the copoiymer.

LEONARD mcnom Hycar Synthetic Rubber-Softener Study. vol. GEORGE KESSLIN. 2, 1941- REFERENCES CITED The following references are of record in the file of this patent: 

